1. Field of the Invention
This invention relates to an apparatus and method of manufacture for a green tire and in particular for supplying a tire component, for example, a reinforced fabric material usually of steel cord, such as is used for a tire carcass or a steel breaker which is fed as a predetermined cut length to a green tire building drum. This operation involves cutting, separating the cut component from the following continuous portions and guiding the cut component with positioning thereof.
2. Description of Related Art
Generally, green tires are manufactured by several steps. A first step is to build or assemble a cylindrical tire carcass by fitting a pair of beads one over either end of the cylindrical carcass, folding back the two ends of the cylinder around the beads and attaching two sidewalls to form a green carcass. Secondly a belt reinforcement is formed and then fitted around the green carcass which is shaped up into a toroid and bonding the belt to the green carcass. Finally tread is fitted. In the belt forming process, tire components or tire materials (for example, tow plies of steel breaker, a reinforcing band and a rubber tread strip) are supplied in turn in a direction perpendicular to the axis of a belt building drum to a belt assembly stage, the components being in order of winding and fitting to the drum to form an annual belt/tread assembly.
Each breaker as mentioned comprises sheets of fabric in the shape of a long belt or sheet in which many parallel steel cords are incorporated. The cords are at an acute angle to the longitudinal direction, and are embedded in rubber.
A conventionally known process for supplying this breaker to a belt building drum comprises unwinding the breaker from a reel into a transfer apparatus with guides and control to avoid a snaking feed, placing the breaker into a place for measurement of its length and cutting it, and after cutting off the required length, sending the cut breaker onto a guide pan for positioning and then supplying the cut breaker to the belt building drum in a direction perpendicular to the drum axis, and fitting it on to the drum. (For example, Japanese Examined Patent Publication SHO 53-24483).
An apparatus in which this process is put into execution is disclosed in the same Japanese Examined Patent Publication Sho. 53-24483. The apparatus comprises unwinding means for unwinding the breaker from a reel; a guide mechanism for correcting snaky feed and means for determining the breaker fabric position; a conveyor for transferring the breaker; a cutter provided at an intermediate position on the conveyor to cut the fabric to the predetermined length; means for positioning the cut breaker lengths; guide pan conveyors for the breaker lengths set up to have upper, middle, and lower levels (guide pan) for supplying in a direction perpendicular to a drum axis the cut breakers to a belt building drum and for attaching them to the assembly on a belt building drum.
The three stage guide pan conveyor for supplying the breakers to the drum has each level independently driven and includes frames for supporting the guide pans so that they may be moved towards and away from the drum by pivoting in a vertical direction.
The breaker fabric has steel cords embedded at an acute angle to the longitudinal direction and the breaker is then cut parallel to the steel cords. To separate the cut breaker length from the length of subsequent breaker material, the conveyor on which the cut breaker lies is operated so that its downstream sector is driven and its upstream sector on which the top portion of the subsequent long length breaker is not driven.
In this position, the breaker is already cut at the acute angle and thereby a rear triangular portion (this triangular portion is produced by the slant cut) of the cut breaker lies on the non-driven upstream sector. As a result, when the downstream conveyor sector is driven to convey the cut breaker, the conveyor sector on which the rear triangular portion lies is not put into drive, movement of the breaker by the downstream sector casuses slipping and resultant sideways displacement and in many instances irregular elongation of the rear triangular portion.
Further, in such a conventional conveyor the guide pan apparatus is complex in structure and needs a large area to include a standby position and is expensive to maintain. Such conveyors use guide rollers to accurately place the breakers in alignment with the center of the drum and such alignment devices are not very effective.
Still further, the drum for attachment of the breakers has conventionally not been provided with a means for positioning the breaker with accuracy, which has caused difficulty in supplying and attaching the breakers accurately onto the drum, and all these problems require complex structures and frequent adjustment in the building operation.